亚临床甲状腺功能减退大鼠骨代谢改变及左旋甲状腺素疗效

Change of bone metabolism in subclinical hypothyroidism rats and the improvement of L-thyroxine treatment

目的探讨亚临床甲状腺功能减退(SCH)模型大鼠骨代谢改变及应用左旋甲状腺素(L-T4)治疗后的疗效。方法健康Wistar雄性大鼠60只,随机分为3组:亚临床甲减组(SCH组)、L-T4替代治疗组(SCH+T4组)、对照组(C组),每组20只。测定不同组别大鼠血清血脂、骨碱性磷酸酶(BALP)、抗酒石酸酸性磷酸酶(TRACP-5b)和骨密度(BMD)。比较不同组别大鼠甲状腺功能、骨代谢指标、骨密度及血脂相关指标的改变。结果 SCH组大鼠TRACP-5b(F=301.214,P<0.05)、BALP(F=16.432,P<0.05)、BMD(F=8.112,P<0.05)明显低于对照组。胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)高于对照组(P<0.05)。L-T4组大鼠促甲状腺激素(TSH)恢复至正常范围,TRACP-5b、BALP有所升高(P<0.01),TC、LDL-C有不同程度下降(均P<0.05)。相关分析显示,TSH水平与TC(R=0.425,P<0.05)、LDL-C(R=0.228,P<0.05)呈正相关,与BALP(R=-0.297,P<0.05)和TRACP-5b(R=-0.265,P<0.05)呈负相关。结论 SCH是骨质疏松的重要危险因素,可能通过升高TSH抑制骨细胞活性而降低骨密度,L-T4可部分改善实验大鼠骨代谢异常。

Objective The purpose of our study was to observe the changes of bone metabolic markers , bone mineral density and lipid metabolism in subclinical hypothyroidism rats and the effect of L-thyroxine （ L-T4 ） treatment on these changes in the short term.Methods Twenty male Wistar rats SCH, SCH＋T4, and control groups were established. Rats in group SCH＋T4 received L-T4 replacement treatment to achieve euthyroidism .Results According to our study , SCH rats had higher total cholesterol （ TC） , low-density lipoprotein cholesterol （ LDL-C） levels （ P〈0.05 ） and lower bone mineral density （BMD） （F=8.112, P〈0.05）, bone alkaline phosphatase （BALP） （F=16.432, P〈0.05）, tartrate resistant acid phosphatase （ TRACP-5b） levels （ F=301.214 , P〈0.05 ） compared to euthyroid subjects .TC, LDL-C decreased and BALP, TRACP-5b levels increased significantly after L-T4 treatment （P〈0.05）.TSH was posi-tively correlated with TC （ R=0.425 , P〈0.05 ） , LDL-C （ R=0.228 , P〈0.05 ） and negatively correlated with BALP （ R=-0.297 , P〈0.05 ） and TRACP-5b （ R=-0.265 , P〈0.05 ） .There was no significant change in BMD after the treatment （ P〉0.05 ） .Conclusion We concluded that SCH is closely associated with bone metabolism changes and osteoporosis, which were partly improved by L-T4 treatment.In the short term treatment, the changes of BMD had no sta-tistical significance .